IC interconnect system using metal as a mask

Abstract

During the manufacture of semi-custom monolithic integrated circuits or semiconductor devices silicon wafers with P-type or N-type impurity regions are used and interconnections must be produced for specific applications. Unlike currently known technologies, an electrically conductive film containing standardized openings in a pre-arranged raster is deposited on the silicon wafer. Subsequently, the conductive film is removed between preselected openings directly or indirectly by means of electromagnetic radiation in order to produce the required circuit configuration. A laser beam is particularly appropriate therefor because such beam can be positioned and controlled and can be used directly for the exposure of a photosensitive film. The production of isolated conductive areas in the conductive film is then accomplished by photo-etching. The use of an expensive customer specific photomask can thus be avoided. In the thus obtained semiconductor device the conductive film contains a regular arrangement of openings which form the ends, sides or corners of isolated conductive areas.

Accordingly, What we claim is: 
     
       1. A monolithic integrated semiconductor device comprising: a silicon wafer;   said silicon wafer comprising a substrate possessing a multiplicity of impurity-doped regions;   an insulating layer covering said substrate of said silicon wafer;   a conductive film covering said insulating layer;   a predetermined number of at least in part regularly recurring contact surfaces associated with related ones of said impurity-doped regions;   said insulating layer containing a prdetermined number of at least in part regularly recurring openings which are associated with said predetermined number of at least in part regularly recurring contact surfaces;   a preselected number of said at least in part regularly recurring contact surfaces being connected with said conductive film;   said conductive film containing at least in part a substantially regular pattern of openings;   a predetermined number of isolated conductive areas formed in said conductive film and separated from each other;   each one of said isolated conductive areas being defined by a preselected number of said openings of said substantially regular pattern of openings of said conductive film and by a preselected number of substantially linear openings defining substantially straight lines formed in said conductive film and interconnecting said preselected number of openings of said substantially regular pattern of openings of said conductive film; and;   each said predetermined number of isolated conductive areas containing at least one of said regularly recurring openings associated with one of said regularly recurring contact surfaces.   
     
     
       2. The seminconductor device as defined in claim 1, wherein: said conductive film containing at least in part said substantially regular pattern of openings, contains a predeterminate pattern of openings.   
     
     
       3. The semiconductior device as defined in claim 1, wherein: said preselected number of openings associated with each one of said isolated conductive areas are selectively arranged at ends, corners or sides of said isolated conductive areas.